I want to change the aspect ratio of an AVI video. All online sources recommend MPEG4Modifier but whenever I try to run the MPEG4Modifier.exe program file all I get is "MPEG Modifier has encountered a problem and needs to close. We are sorry for the inconvenience." The latest version also offers to send an error report. OS is XP Pro. I have tried several versions of MPEG Modifier, including the command line version, always with the same result - and yes, I do have Microsoft .NET Framework installed. I am extremely confused about .NET Framework. Is the version critical? A system requirement for MPEG Modifier is .NET Framework 2.0. Add/Remove Programs says I have .NET Framework 2.0 SP2, and if I click 'support information' it says "Version: 2.2.30729". There is a .config file with the current MPEG Modifier that includes: <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0" /> <supportedRuntime version="v2.0.50727" /> In my WINDOWS\Microsoft NET\Framework\ are sub-folders v1.0.3705, v1.1.4322, v2.0.50727, AND v3.0 and v3.5 folders. I've downloaded what I think is .NET Framework 2.0 (not SP-anything). What happens if I just attempt to install this over what I have at present?